Intrusion detection system

Abstract

Systems and methods for intrusion detection, including an intrusion detection device configured to send a light source to a retroreflector and receive reflected light from the retroreflector. An alarm is activated if the light source is not detected by the intrusion detection device. The intrusion detection device includes a computing device coupled to a preamplifier, a superregenerative receiver, and a digitizer.

What is claimed is: 
     
       1. An intrusion detection device comprising:
 a light source for projecting a light beam across a distance, wherein the light source is periodically modulated at a frequency; and 
 a receiver comprising:
 an optical transducer; and 
 a superregenerative receiver coupled to the optical transducer and configured to periodically oscillate at the frequency the light source is modulated at, whereby reception of the light beam by the optical transducer will influence the superregenerative receiver to oscillate sooner than if the light beam is not received. 
 
 
     
     
       2. The intrusion detection device of  claim 1 , the receiver further comprising a preamplifier configured to receive a signal from the optical transducer and output an amplified signal to the superregenerative receiver. 
     
     
       3. The intrusion detection device of  claim 1 , the receiver further comprising a digitizer configured to receive an oscillated signal from the superregenerative receiver and in response output a digital signal. 
     
     
       4. The intrusion detection device of  claim 3 , further comprising: a housing; a computing device housed in the housing, the computing device including a processor, a memory coupled to the processor, software stored on the memory and configured to run on the computing device, and a clock. 
     
     
       5. The intrusion detection device of  claim 4 , wherein the computing device is configured to receive an indication that the superregenerative receiver is oscillating and to determine whether a time lapse between modulation of the light source and receiving the indication exceeds a time the modulated light beam can influence oscillation of the superregenerative receiver, wherein an indication of an alarm is output by the computing device in response to the modulated light beam not being received. 
     
     
       6. The intrusion detection device of  claim 5 , further comprising a signal coupling the computing device to the receiver whereby at least one component of the receiver is turned on and off. 
     
     
       7. The intrusion detection device of  claim 5 , further comprising an alarm module coupled to the computing device and configured to output an alarm signal in response to receiving the indication of the alarm. 
     
     
       8. The intrusion detection device of  claim 5 , further comprising a connection to a wireless network coupled to the computing device and configured to communicate an alarm condition and other information to and from the wireless network. 
     
     
       9. The intrusion detection device of  claim 8 , further comprising a camera coupled to the computing device configured to record images during alarm conditions and normal conditions as requested and transmit them over the wireless network. 
     
     
       10. The intrusion detection device of  claim 4 , the computing device further configured to output a signal to the superregenerative receiver, whereby oscillations of the superregenerative receiver are reduced to zero. 
     
     
       11. The intrusion detection device of  claim 4 , the computing device further configured to perform an initial calibration routine to adjust at least one of a frequency of the superregenerative receiver and a modulation frequency of the light source until they are the same. 
     
     
       12. The intrusion detection device of  claim 4 , the computing device further configured to determine if a time-to-oscillation length is within a normal range, and upon determining that the time-to-oscillation length is outside the normal range, tuning at least one of a frequency of the superregenerative receiver and a modulation frequency of the light source. 
     
     
       13. The intrusion detection device of  claim 1 , wherein the light beam is reflected from the light source to the optical transducer. 
     
     
       14. An intrusion detection device comprising:
 a light source for projecting a light beam across a distance; and a receiver to detect the light beam comprising: an optical transducer, and a compound mirror configured to direct the light beam to the optical transducer. 
 
     
     
       15. An intrusion detection device comprising:
 a light source for projecting a light beam across a distance; and a receiver to detect the light beam, the receiver further comprising at least one optical filter that is a dichroic filter to pass only light of approximately the same wavelength as the light source. 
 
     
     
       16. An intrusion detection device comprising:
 a light source for projecting a light beam across a distance; and a receiver to detect the light beam, wherein the light source is a visible laser and is configured to operate in at least two user-selectable modes, a first intrusion detection mode wherein the light source is on for a fraction of the time, wherein the average intensity of the light source is no greater than a microwatt, whereby the light source is not easily seen, and a second alignment mode wherein the light source is functioning as a highly visible laser pointer to aid in alignment of the light source with the receiver.